Method and apparatus for controlling electric motors



METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2, 1920 9 Sheets-Sheet 1 mwk g a a z 5 z 52 2 4P0/e 44/24 2 P0 7e 21% Z6 INVENTOR er W41 Jim 4110 IVEYS Dec. 14 1926. 1,610,455 1 J. D. LEWIS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2, 1920 9 Sheets-Sheet 2 Dec. 14 1926. 11, 10,455

J. D. LEWIS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2 1920 9 Sheets-Sheet 3 Z/ Z2 Z5 24 25' 26 27 Z8 Z9 30 3/ 32 33 34 35 INVENTOR w W W A TTORNEVS a 5 c a f Dec; 14, 1926. 1,610,455

J, D. LEWIS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2, 1920 9 Sheets-Sheet 4 ale 4 042 Whd/iy 1W a 3 a 0 n 2a 3/ wwsAaQm u I I I 2 2 H a 2:25 a 3437 a 2135 a 2634 a 2 a 4 fi g ya m v I I l 3/ 1 a a a a e ll INVENTOR POLE I my: gw Km 45; ATTORNEYS Dec. 14, 1926. 1,610,455

J. D. LEWIS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2, 1920 9 Sheets-Sheet 5 9 4P0/8A62m/100M 24 v 22 L625? W Q ll ll ll Q ll 6 ll '3 ll 1: 2/ w'aa' 21' 27' 30 21 30 2a 32 22 a/ PoLE WINDING qpOLE WINDING- ATTORNEYS Dec. 14, 1926. 1,610,455

J. D. LEWIS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2, 1920 9 Sheet s-Sheet e INVENTOR m ATTORNEYS Dec. 14 1926. 1,610,455

J. D. LEWHS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Se pt. 2. 1920 9 Sheets-Sheet v /gfi1 abcdefabcdfabcdefabcdef &

IN l/E N TOR WWW 4W ATTORNEYS Dec. 14 1926.

METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS LEWIS 9 Sheets-Sheet 8 Filed Sept. 2, 1 920 MQQQW Dec. 14 1926.

D J. D. LEWIS METHOD AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS Filed Sept. 2, 1920 9 SheetsSheet 9 Q3 Rn kw K MQQQN a f P? n kw UJQQW 42w ATTORNEYS l mented @ec. ltd, 1926.,

UNITED STATES remiss PATENT Fries.

JACCB D. LEWIS, CF YONKEBS, NEW YORK, ASSIGNQR TO OTIS ELEVATOR COMPANY, A

CQE'PDRATIDN 01F NEW JERSEY.

it!?E'llflfiiil] AND APPARATUS FOR CONTROLLING ELECTRIC MOTORS.

Continuation ofepfielicetion Sierial No. 268,183,'fi1ed December 24, 1918. This application filed September f8, 19%. Serial No. 4023741;

,li ly invention relctes to alternating current electric meters of the asynchronous or induction type and particularly to methods and spparetus for varying the speed thereof.

in certain uses oflinduction motors, for example, in connection with elevators and hoists, it is necessary to maintain a continuous torque end in all uses Where the load is constantly upon the motor any changes of speed Which involve breaking of connections give rise to excessive arcing or burning ot the switch contacts and to "the occurrence of excessive flows of current. It is an object of my invention to provide 21 method and apparatus for varying the speed of induction motors without interruption of the torque and Without such breaking of the contects es gives the undesirable results above mentioned.

Another objectof my invention is to provide on induction motor with s Winding for producing o plurality. of rotating fields respectively having different numbers of poles in which the effect of each number of poles may be secured at difi'erent times, and s rotating field maintained during any change from one number of poles to another.

Another object of my invention is to pro vide on induction motor with s Winding having a plurality of ports for respectively producing ditlcrent numbers of poles in which each part may be rendered effective clone to produce its respective number of poles end rotating field muintsined while u change is made from operation with one port of the Winding to operation with another part of the Winding.

Another object of my invention is to provide o Winding for on induction motor consisting of a plurality of ports capable of being connected for simultaneous energizotion and arranged to produce rotating fields hoviug respectively different numbers of poles, for example, by having corresponding portions of the several parts connected in series, (i, e., with the portions of the parts respectively utilizing current of the same phase connected in series), in which e rotating field of one number of poles may he obtained by rendering ineffective the ports of the windings arranged to produce nnother numher, or other numbers, of poles. A further object of my invention being to insure the rendering effective of one part or the Windin contacts.

Another object of my invention is to provide anunductrou motor having a. Winding comprising a plurality of parts respectively arranged to produce different numbers of poles With corresponding portions of the windings arranged for simultaneous energizotion wherein short circuiting ell ports of the Winding, except those producing the desired number of poles, produce the desired speed. Aiurther object of my invention is to arrange the short circuited portions of the windings so that any current induced in them by the non-short-circuited portions will be neutralized and of no harmful efiect.

Another object of my invention is to provide on induction motor having a Winding comprising a plurality of parts producing respectively rotating fields having diiierent numbers of poles each part being capable of being rendered operative and inoperative, and'certain of said parts being cnpable of being rearranged to provide. different nu hber of polesa.ll Without interrupting the torque or motor.

Another object of my invention is to pro vide a method of altering the connections and arrangement of circuits of on induction motor to secure a plurality of different dei inite speeds Without interruption of the torque of the motor or breaking ofmein circuits.

Other and further objects will appear from the following description taken in connection with the accompanying drawings and will be pointed out in the hereunto.appended claims:

' In the drawings in which like reference characters indicate similar parts, Figure. A is a diegrornmatic showing of a motor and means for changing the connections thereof to produce difierent speeds embodying my. invention. I

Figures B, B and B are diagrammatic showings of the different connections roduced by the controlling mechanisms :1 ustrated in Figure A. l

Figures 13 end B diagrammatically show Gill ill

Figures .1) and I) together diagranini-at ically show'l'a'two-fiphase statorwinding for an inductionniotor' and having parts which are respectively susceptible of arrangement to produce 2 and- 6 pole fields and 1 and-12 pole fields.

Figures E and E together diagrammatically show the manner of altering the connections of the winding shown in Figures D and D in order to produce 4 speeds in ac-- cordance with my invention.

One construction embodymg my 'lIlVQIlt1on includes a WlIldlIlg for induction motors which has parts to produce respectively 7 different numbers of poles, and any of these parts may be so arranged, and provided with means such that its connections may be so changed that it will produce still another number or other numbers of poles. In such an exemplary construction a motor may have a winding comprising two parts connected in series producing respectively different numbers of poles. One part can be rendered ineffective to produce its number of poles, as by short-circuiting, and then while the two parts remain connected in scries the short-circuit may be removed from the first part and placed over the other part so that the other number of poles is produced. Furthermore while one of the parts is short-circuited its connections may be rearranged in various ways so that a number of poles may be produced by it when the short circuit is removed from it, difi'erent from the number formerly produced by it. And during all of these changes the motor connections are never broken and the torque is continuous.

In carrying out my invention a stator winding of an induction motor comprising a plurality of parts respectively for producing different numbers of poles has the portionsof the two windings utilized by the same phase connected in series. For the purpose of fully disclosing my invention I hereinafter describe in detail the manner of utilizing certain stator windings but it is to be understood that any stator windings may be used which may be so connected as to produce respectively different numbers of poles and which may each be susceptible of rearrangement in themselves to produce different numbers of poles such, for example.

as windings made in accordance with the disclosures of my copending ap lication Scrial No. 333,490fi1ed October 2 1919.

Certain of the features disclosed herein are disclosed in my co-pending application Serial No. 268,183 filed December, 1918, of which this application is a continuation.

As a simple embodiment of my invention there is illustrated in Figure A a winding For an induction motor and controlling means for changing the number of poles produced by the winding. The stator winding comprises a three-phase circuit having the coils or groups of coils, a, a and a for producing one number of poles and having respectively connected in series therewith the coils or groups of coils b, b and b for producing a -higher number of poles. Threephase alternating current is carried into the motor by the conductors 4, 5 and 6 which are provided with a main line switch 7.

The flow of current to the motor is controlled by the switch G which might be positioned in an elevator car. The reversing switches H and K as well as line switch L are controlled by the operating switch G.

.The operating switch G comprises a-controller handle carrying a contact 8 which when swung in one direction will sweep over the contacts 9 and 10 and when swung in the other direction will swing over the contacts 9 and 10. If the operating handle is swung to the left to the position I the contact 8 will be swung into contact with the member 10 and current will flow from the main line wire 6 through the conductor 11 to the controller arm through the contact, 10 to the relay 12 which will draw up the armature of the reversing switchK. From the relay 12 the connection is made through the wire 13 back to the main line wire 4. When the armature of the reversing switch K is raised the motor will be connected for one direction of ope-ration as follows. The current'fiowing through the conductor 6 will be carried to the conductor 14: and thence to the terminal of the stator coils a and b. The conductor 14 being energized, the current will flow from main line wire 6 through the relay 13' to the main line wire 4 and draw up the armature of the main switch L thus connecting the main line wire 5 to the conductor 15 which is in turn connected to the terminal of the stator coils b and a through the reversing switch K. v The main line wire 4 will also be connected to the terminal of the stator coils b a -by the switch L. Now the speed relay M is not energized and will be in the position shown so that conductor 1 leading from a point between the coils a and b the conductor 2 leading from a point between the coils a and b and the conductor 3 leading from a point between the coils a and b will form a short circuit around the coils a, a anda producing the connection shown in Figure .the conductor 2 short circuits thecoil b and the conductor 3 short circuits'the coil b producing the connections-shown in Figure B. It will be apparent that mo-v'ement of the operatingglevenof -the switch G to the right to the positions I, I, will energize the relay 12' so as to connect the windings in a difierent relation and produce a difi'ere'nt direction of running. It will now be apparent that an induction motor having a winding with two parts respectively, in series and for producing different numbers-sofpoles has been so connected as to start up on the part producing a higherfnumber of poles, and the connections changed so as to operate the motor finally on the windings producing the lower number of poles and that the torque of the motor has not been interrupted during the transition because during the slight interval while the speed relay M is shifting from one position to another the partsof the winding for. the-higher and lower pole nun? hers are in series as shown in diagram Figure B". It will be observed that in the construction described the speed controlling switch M is redisposed by gravity or equivalent expedient to a position wherein the windingnart producing a higher number of poles will alone be energized. the other part being rendered ineffective by short-circuit when thccurrent is first suppliedto the motor, and that the switch M maybe operated to a position wherein the windingpart producing the higher number of poles is rendered inoperativebyvshortscircuiting and then the part producing the lower num- '.ber of poles is alone effective. It will also be observed'that during this transition from vtheo'higher number of poles must be conthe use of the higher number of poles'alone to the use of the lower numberrof poles alone the part producing the. lower number of poles is energized before the part producing;

the higher number of poles is tie-energized. It has'been proposed heretofore to provide an induction motor with one winding producing a higher number of poles and another winding to produce a lower number of poles and to energize both windings, during the. starting of the motor and to then tie-energize the winding producing the lower number of poles so that the motor will operate only with the winding producing the higher number of poles, but it will be apparent that acwhich are definite in that they are produced 4 by poles normally arranged, i. e., equidistantly spaced, at each speed, the lower speed occurring when the winding-part producing a higher number of poles is energized and the higher speed occurring when the winding-part producing the lower number of poles is energized.

If two parts of a winding produce respec tively numbers ofpoles bearing an even ratio to one another, then the neutralization of the "oltages produced in the short-cir cuited part-of the winding by the current passing through the energized part of the winding is brought about as follows: -(-'(L)*If the motor is running at a'lowv speed with the part of the winding producing a low number of poles short-circuited, there will be no voltage induced in the coils producing the-lower number of poles, because the coils producing the lower number of poles each embrace 360 electrical degrees or the equivalent thereof of the part of the winding producing the higher number of poles, therefore the high speed winding can be connected with Y or A connection while short-circuited.

(b) If the motor is operating on the part of the winding producing the lower number of poles some voltage will be induced in the part of the winding producing the higher number of poles. In order to safely shortcircuit the part of the winding producing the higher number of poles. it must be Y- connectedtor it maybe A connected if,

the coils of the part of the winding producing the higher number of poles are arranged in groups as shown. so that voltages induced in these groups of the part of the winding producing the higher number of poles neutralize one another and the voltage at the shortcircuit point is zero. It will be apparent that if the coils are of full pitch, the coils of the part of the winding producingthe higher number of poles will embrace 90 electrical degrees of the part of the winding producing the lower number of poles, and therefore the part of the windingproducing nected Y or arranged in groups, and the groups connected as above described and as shown, so that the voltages induced in the Ian v lengthened or shortened so that it will ema plurality of numbers of poles.

embod ed in the same motor.

brace 360 electrical degrees or the equivalent thereof of that part-of the winding producing the higher number of poles. The manner of employing coils of shorter or longer pitch than the pole pitchis disclosed in my co-pending application .above identified.

(1)) If the motor is operating on that part of the winding producing a lower number of poles, some'voltage will be induced in each coil of that part of the winding producing the higher number of poles and. the harmful effect of these voltages are avoided by connecting that partof the winding producing the higher number of poles in a Y-connection or by connecting them in a A connection and arranging the coils in groups and distributing the groups as shown so that the voltages produced in these groups neutralize one another and the voltage at the short-circuit point is zero.

While I have so far disclosed the idea of providing a plurality of winding-parts producing different speeds and dc-energizing one winding-part and energizing the other in order to obtain difierent speeds, but always energizing another part before any given part is de-energiz'ed, my invention also includes the idea of having each of the parts so arranged that while it is deenergized the internal connections thereof may be changed so that it will itself produce a plurality of numbers of poles each different from the numbers of poles produced by any other part even though the connections of such other parts or part may be changed so that they individually produce In order to illustrate and disclose the manner of carrying out the idea of changing the connections of each part of a winding to produce different numbers of poles there are illustrated in Figures B and B two parts of a 3-phase winding that may be be changed from a 4 pole to a 12 pole winding-part. The contacts 18, 20 and 19 are respectively for connection of the three supply wires I, II and III Inasmuch as the mak- The part ing of a drum controller to produce a num-' ber of connections is merely a matter of design after the connections are disclosed I have refrained from showing any drawings oi controllers but in Figures C and C I have shown the manner of connecting up the various lettered groups of coils by indieating what terminals are t-o'be brought together so as to carry out 4 different changes of speed in accordance with my invention. In Figure C the Diagram 1 shows the manner of connecting the coils of parts B and B so that a twelve pole winding and a six pole winding are connected in series. This will be the arrangement of the connections for-starting. It will be apparent that when winding-parts producing difierent numbers of poles are both energized the motor will six poles. The next speed will be produced by the six pole winding alone and in order to reach this condition without break of motor connections there is a transitional stage shown in Diagram 1 wherein the six and twelve pole parts are in series.

Diagram 2 shows thesecond speed wherein the motor is operating on the six pole part and the twelve pole part is short circuited. It will be noted that this speed is arrived at by energizing the part producing the desired speed before the part producing the former speed is die-energized. The next speed desired will be that produced by four poles and therefore in Dim gram 2 I have shown the manner of altering the connections of the part Figure B to change from a twelve pole winding to a four pole winding. These changes occur while the part is de-energized. Before deenergizing the six pole part the four pole part is energized and Diagram 2" shows this transitional condition. Diagram 3- Figure C shows the condition wherein the motor is operating on a four pole winding-part which is A connected so as to produce the proper flux distribution in accordance with the principles disclosed in my co-pending application above identified. In this case the six pole part is short-circuited.

The next. speed desired is that produced by two poles and therefore I have shown in Diagram 3Tthe manner of rc-arranging the connections of B part while that part is liin tie-energized in order to produce 2 poles;

In orderto avoid interruption of the torque above mentioned, it is necessary to energize this B part before the four pole part B is de-energized and the connections for producing this transitional condition are inclicated in Diagram 3".

The fourth speed obtained by the use of 2 poles in A connection is then obtained by deenergizing the 4 pole part B and the Diagram 4 shows the connections to produce this result.

My invention also includes the idea of applying my invention to 2-phasemotors and in Figure D I have shown a 2-phasc winding having parts for producing 2 and 6 poles and in Figure D 4 and 12 poles. In Figure D the leads are carried out from the windings, and numbered 55' to 66 and in Figure D are numbered 55 to 66, so that the connections of the windings may be changed to cause the windings to produce the different numbers of poles mentioned. In Figure D the first-phase conductors .are brought in to the contacts 51 and 52 and the secondphase conductors to the contacts 53 and 54. It will be observed that changes in the connections between the leads which are brought out change the connections of groups of coils, the coils of one and the same group having the same letter. In Figures E and E I have shown a series of diagrams which disclose the manner of altering the connections of the two winding's'shown. in Figures D and D in order to produce four diflerentspeeds, the different speeds being produced in accordance with the principles of my invention. It will be seen from the diagrams of Figures E and E- that the transitions from one speed to the other are carried out withoutthe interruption of the torque of the motor'just as in the case of the 3-.phase motor above described.

lVhile it has been proposed, in theprior art, to have in an induction motor windingsv producing-xdiiferent numbers of poles and using both windings in starting and then rendering the winding producing the lower number of poles inoperative after the speed corresponding to the higher number of poles is obtainedas above mentioned my invention relates to the idea of providing a plurality of windings each producing a different nu'mher or, poles (and each of these windings may be rearranged in itself to produce several numbers of poles) and in starting rendering only one of all these windings operative and in running also, except for a brief transition; from one winding to another, but without interrupting, the torque of the motor because the succeeding winding is energized before the preceding winding is deenergized. And whiie I have illustrated and described and 3-phase windings SUS."

ceptible of alternation to effect certain speed ratios it is apparent that the substitution of any other windings such, for example, as those disclosed in my co-pending application above identified constitutes merely a matter of engineering. Myinvention therefore is not limited to the exact details of the construction above described but is defined in the hereunto appended claims.

Having thus described my invention, What I claim as new and desire to secure by Letters Patent is:

1. In combination, a multi-speed induction motor having independent inducing windings for producing different speeds, means for energizing the windings for any one speed without energizing those for the other. speeds, and means for connecting said independent windings in series to the supply circuit.

2. In combination, a multispeed induction motor having independent inducing windings for producing different speeds, means for energizing the windings for any one speed without energizing those for the other speeds, means for changing the energization from one winding to another and means for connecting said windings in series to the supply circuit during said change.

3.'In combinatioma multi-speed induction motor having independent inducing windings for producing different speeds, and means for selectively short-circuiting the windings for the different speeds, said windings being in series during the transition period from one speed-to another.

4. In combination, a multi-s )eed induction motor having two indepen ent inducing windings of different pole numbers, and means for; fully energizing either one of said windings and for short-circuiting the other to cause the motor to run at either one of two speeds, determined by the pole number of the winding energized, and for energizing both'ot said windingsin series relation and thereafter short-circuiting'said one winding and fully energizing the other to change from said one speed to the other.

5. In combination, a multi-speed induction motor having two independent inducing windings of difierent pole numbers, and means for alternatively fully energizing either one of said windings while short-circuiting the other winding to cause the motor to run at either one of two speeds determined by the pole number of the winding energized, said means comprising means for energizing bothof said windings in series relation during the transition from one speed to the other.

6. In combination, a multispeed induction motor having at least two inde endent inducing windings for producing ifferent speeds, means for selectively short-circuiting the windings for the different speeds,

and means for reconnecting at least one of said windings while short-circuited to pro: duce another difierent speed.

' 7. In an induction motor, a Winding comprising a plurality of parts for respectively producing diiferent numbers of poles and series connected for energization, and means for rendering any of said parts inoperative whereby a plurality of definite speeds is secured, oneiof said parts being susceptible of rearrangement while inoperative to produce difierent numbers of poles. 8. In combination, an induction motor having a winding comprising parts for respectively producing difierent numbers of poles and connected for simultaneous energization, and means including a switch biased to a position wherein said means renders inoperative one of said parts and movable to a position wherein said means renders inoperative the other of said parts.

9. The method of producing different.

speeds in an induction motor which consists inarranging the connection of the inducing winding to cause difierent parts of it to produce'respectively a plurality of numbers of poles, connecting said parts in series for energization, and renderin each part operative alone by rendering a l other parts inoperative. I, g

10. The method of producing different speeds in aninduction motor which consists in arranging the connections of the winding to cause diflerent parts of it to produce re spectively a plurality of numbers of poles,

connecting said parts in series for energizetion, rendering each part operative alone by rendering all other parts inoperative, and altering the connections of any one of said 1 arts to arrange it to produce difierent numers of poles while said part is inoperative.

11. The method of producing 'difl'erent v incident speeds in an induction motor which consists in connecting the inducing winding to provide parts producing respectively difierent numbers of poles, connecting sald parts in series for energization, and selectively deenergizing any or. all but one of said parts according to the speed desired.

12. The method of producing different speeds in an induction motor which consists in connecting the winding to provide arts producing'respectively different numers of poles, connecting said parts in series for energization, and selectively deenergizing any or all but one of said parts according to the speed desired, and rearranging the connections of any deenergized part to produce difierent numbers of poles and reenergizing such part.

13. The method of producing different 1 speeds in an induction motor which consists in connecting the winding to provide parts.

producing respectively different numbers of poles, connecting said parts in series for energization, and short-circuiting any or all but one of said parts according to the speed desired, insuring that any part to be shortcircuited be previouslyarranged in Y-con- Jason D. Lewis 

